Power tube anode



"se t 1, 1936. J. o. B IENTII IEY 2,053,126

POWER TUBE ANODE Filed Sept. '19, 1951 Inventor.

Jetson 0. Bentley, b MW His Attorney.

Patented Sept. 1 1936 I UNi'lED STATES 2,653,126 rowan TUBE A'NODEJetson 0. Bentley, Castle Point, N. Y., assignor to General ElectricCompany, a corporation of New York Application September 19, 1931,Serial No. 563,850

11 Claims.

The present invention relates to electron .discharge devices of thepower type and more especially to their electrode construction.

One of the most difficult problems encountered in power tube design isthat of the anode ,construction on account of the fact that this memberiscalled upon to dissipate large amounts of heat energy from arelatively small surface. The problem is accentuated in the case of tubedesign necessitating a flat anode of thin material, operated atrelatively high temperature and in which thedistances between the anodeand adjacent electrodes are relatively small in order to obtainthe-desired operating characteristics. The slightest warp or distortionof the .anode under these conditions causes objectionable deviations inthe tube characteristics and inasmuch as he distortion usually becomesworse after long service of the .anode, the latter may in time contactwith the adjacent electrode and cause a short circuit.

.One of the objects of the present invention is to provide an improvedanode construction for powertubes which will not bow, .warp or'diStQrtin any manner when subjected to heat, under operating conditions. A moregeneral object is to improve the construction and operation of powertubes with the view toward maintaining their electrical characteristicssubstantially constant.

Inthe. past, it has been customary to meet the problem of anodedistortion, by which term, I mean relative changes in space of anyportion of the member, whether due to Warpin bowing orotherwise, byrigidly bracing-the electrode in a heavy frame. The idea underlying thisprior art design was to offer equal and oppositeiorces to thoseexercised by the expanding member. -I:I ow ever, this form ofconstruction has not been altogethersatisfactory, particularly in thosecases where the anode material is relatively thin and of extensive area.Accordingly, I propose an improvement of design which may be used quitegenerally for electrode constructionbut which is especially desirableinv the case of fiat an odes of thin stock, employed in connection withsmall inter-electrode spaces. The principle of operation which I employin accordance withthep esentinvention differs from that of thepriorartin that practically all parts of theimprovedanode are givenfree. and unhampered opportunity to expand with thechanges oftemperature, the freedom of movement being afforded without causingany-changein the operating characteristics of the t be.

In ca ry n out the i en i n, .1 div de th anodeinto ;a number ofsections which are held in a frame in such a manner that they may expandfreely in all directions when heated. In addition to allowing freeexpansion, the improved construction lends the further advantage ofeffecting a substantial saving of anode material, since the sections maybe salvaged from other tubes, or may be cut in an economical manner fromthe raw sheet stock. The sections may also, be made of much lightermaterial than the prior art anodes, which not only tends to reduce thecost of material but also facilitates the ease with which the materialis worked.

The invention will be better understood when reference is made to the,following description 15 and the accompanying drawing in which Fig. 1shows a tube in elevation containing an anode improved in accordancewith my invention; Fig. 2 is a perspective view of the improved anode,in partly disassembled form; Fig. 3 is an enlarged view of a cornerportion of the assembled anode, Fig. 4 is ,a .;crcss-section taken alongline 44 of Fig.3; while .Figs. 5, 6 and 7 show modified forms of slatswhichlin theirassembled form mayconstltu-tethe active portion of ananode.

Referring to Fig. 1, numeral l designates the envelope of a highlyevacuated tube containing a filamentary cathode 2, an electrostaticcontrol member 3 andarectangular anode 4, closely surrounding thecontrol member. As will be seen from the illustration, the electrodeshave relatively large active areas and the inter-electrode spacesarerelatively small in order to obtain the proper operatingcharacteristics. The envelope terminates in a pair of oppositelydirected stems to which are secured clamp members 5 for supporting theelectrode structure in the usual manner. Inasmuch as the electrodesupporting structure and the relative arrangement of the electrodes arewell known in the art, it is unnecessary to present adetaileddescription other than to state that in tubes of this character, it isessential that the anode shall remain .free from warping, bowing orother form of distortion in order ;-that the ,device may efficientlytranslate electrical energy. When aztube of this sort is provided with.a-nanodeof the prior art design, theactive surface of which ordinarilyis made of sheet metal in one piece, there is a tendency for the center,of the anode, which usually is the hotter ,portion, to bow in towardthe control member under the influence of heat employed during ,exhaustor generated by the filament and load currents in operation. Inorder topreclude this deformation of shape, ithasbeen proposed heretofore toprovide the anode with strengthening ribs or fins which extend over thecentral part of the anode so as to offer a restraining force to thisbowing effect. Sometimes the prior art anode would warp from corner tocorner and change the line-up between the electrodes. An anode, improvedin accordance with the present invention, positively avoids these bowingand warping effects without necessitating ribs, fins or otherstrengthening members.

I propose to divide the anode into a number of sections 6, as slats orstrips, shown more clearly in Figs. 2 and 5, arranged side by side, inedgewise relation so as to form a continuous surface, also securedtogether in a flexible manner by a frame of relatively light material.These slats may be fabricated of any suitable material and in the caseof large power tubes, are usually constituted of molybdenum. I prefer tomake this subdivision along the direction of the shorter or transversedimension of the anode, although it will be understood that I may, ifdesired, arrange these slats in the longitudinal direction of the anode.The frame consists of two pairs of U shaped side members I, 8, alsopreferably of molybdenum, one of each pair, the member 8 as shown,fitting within the other member 7 so as to leave a space between theflange portions which receives the end of each slat nearer thereto, in asliding fit. The slats may be inserted between both adjacent pairs ofthe flange portions so that the anode surfaces, designated as a whole bythe reference character 9, are arranged in opposed relation, and at'sucha distance apart 'as to provide the proper inter-electrode space whenassembled in the tube. The side members I, 8 are held together by meansof two adjacent pairs of cross pieces Ill, preferably of the samematerial as the side members, these pieces having a U-shape with flangeportions which embrace the upper edges of the two uppermost slats andabut the lower edges of the lowermost slats. The side and cross piecesare secured together at their corners by rivets passing through openingsl I, I2 and I9 to constitute arigid frame, as shown complete in Fig. 1.

The dotted line [3 in Fig. 3, indicates the extremity of the .slatswithin the side frame mem bers and it is evident that the distancebetween the latter when assembled should be somewhat greater than thelength of each slat so that the latter can expand freely in itslongitudinal direction. If desired, the slats may be reinforced in thisdirection by one or more fins I 4, formed preferably integral with eachslat as a single upturned member, shown in Figs. 5 and '7, or several ofsuch members as indicated in Fig. 6, positioned conveniently near one orboth of the edges of each slat. The anode structure as a whole mayfurther be strengthened by a rigid U shaped member I 5 disposedintermediate the endsof each slat, preferably midway between, andpassing through suitably shaped apertures cut in the upturned finportions. The member I5 is riveted in a pivotal manner as indicated byreference character IE to each slat and cut away at each end to form atongue which is inserted under the overhanging portions of thecross-members and riveted thereto. The tongue portion of each member I5is provided with a slot I! which registers with a round rivet hole IS ina cross member so as to allow longitudinal expansion of the member. Themiddle portion of the latter is heated to a greater extent than the endpor-. tions and consequently, there is a temperature difference in themember which necessitates a provision for expansion.

From the foregoing description and the accompanying illustration, itwill be evident that the anode slats are free to move in theirlongitudinal direction along which the greatest expansion in thesemembers takes place. Hence, when the improved anode is subjected tosevere heat conditions either in operation or during exhaust, thevarious metal parts may expand freely without causing distortion,warping or bowing of the electrode, as a whole. It has been found thatan electrode construction in which free movement is thus permitted tothe constituent parts thereof, lends itself to the proper anode designof all types of tubes but is particularly desirable in thoseconstructions which require the minimum amount of material used for theanode and in which the inter-electrode spaces are extremely small andcritical.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An anode for an electron discharge device comprising a plurality ofsections forming a continuous surface, said sections being held in aframe which permits movement of the sections with respect to one anotherand with respect to the frame when the anode is exposed to heat underoperating conditions.

2. An anode for an electron discharge device comprising a plurality offlat rectangular strips arranged side by side in edgewise relation, saidstrips being secured at their ends by a frame which permits relativemovement of the strips with respect to one another and with the framewhen the anode is exposed to heat.

3. An anode for an electron discharge device comprising a pair ofopposed rectangular members, each having a dimension greater in onedirection than in the other, said members being constituted along thedirection of greater dimension, of a plurality of sections whichpermit'relative movement therebetween and thereby preclude distortion inthe direction of greater dimension during operation of the anode.

4. An anode for an electron discharge device comprising a plurality offlat rectangular strips arranged side by side in edgewise relation, asupporting frame for said strips which permits relative movement betweenthe strips, said frame consisting of side and cross members fittedtogether so as to leave spaces in which the strips are free to move intheir longitudinal direction.

5. An anode for an electron discharge device comprising a pair ofopposed rectangular members, each having a dimension greater in onedirection than in the other, said members being constituted along thedirection of greater dimension, of a plurality of sections which permitrelative movement therebetween and thereby preclude distortion in thedirection of greater dimension during operation of the anode, and aframe for flexibly holding the sections in place.

6. An anode for an electron discharge device comprising a plurality ofsections forming a continuous surface, said sections being held in aframe which permits movement of the sections with respect to one anotherand with respect to the frame when the anode is exposed to heat, each ofsaid sections being provided with a reinforcing upturned portionextending along its length.

7. An anode for an electron discharge device comprising a plurality ofsections forming a continuous surface, said sections being held in aframe which permits movement of the sections with respect to one anotherand with respect to the frame when the anode is exposed to heat, each ofsaid sections being provided with a reinforcing upturned portionextending along its length, a support for said sections positionedintermediate their ends, said upturned portions being cut away toreceive said support.

8. An anode for an electron discharge device comprising a pair ofopposed rectanguar members, each having a dimension greater in onedirection than in the other, said members being constituted along thedirection of greater dimension, of a plurality of sections which permitrelative movement therebetween and thereby preclude distortion in thedirection of greater dimension during operation of the anode, and aframe for flexibly holding the sections in place, a support for each ofsaid rectangular members, said support extending in the direction of thegreater dimension and pivotally secured to the sections intermediatetheir length whereby relative movement is permitted between each supportand the sections secured thereto.

9. An anode for an electron discharge device comprising a pair ofopposed rectangular members, each having a dimension greater in onedirection than the other, said members being divided along the directionof greater dimension into a plurality of sections which permit relativemovement therebetweeii, thereby precluding distortion in the directionof the greater dimension during operation of the anode, a frame forholding the sections in place, said frame consisting of side and crossmembers rigidly secured together at their extremities.

10. An anode for an electron discharge device comprising a pair ofopposed rectangular members, each having a dimension greater in onedirection than the other, said members being divided along the directionof greater dimension into a plurality of sections which permit relativemovement therebetween, thereby precluding distortion in the direction ofthe greater dimension during operation of the anode, a frame forflexibly holding the sections together, said frame consisting of sideand cross members, a support for each of said sections, said supportextending in the direction of greater dimension and pivotally secured tothe sections at positions intermediate their length whereby relativemovement is permitted between the support and the sections securedthereto, said support being secured to the cross members of the frame byflexible joints.

11. An anode for an electron discharge device comprising a plurality ofmetal sections freely movable with respect to one another underoperating conditions.

JETSON O. BENTLEY.

